French presidential hopeful Francois Fillon has been placed under formal investigation over claims he gave his wife a "fake job".
The conservative candidate has been given preliminary charges which allege he misused public funds and failed to properly declare his assets.
He will appear before a magistrate on Wednesday.
The 62-year-old is alleged to have paid hundreds of thousands of euros in taxpayers' money to his British-born wife Penelope for work she may not have carried out.
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Two of the couple's children, Marie and Charles, have also been interviewed by investigators over claims they held "fake jobs".
Under French law, being put under formal investigation means there is "serious or consistent evidence" that points to probable involvement of a suspect in a crime.
Mr Fillon, a former prime minister and the Republicains party candidate, has repeatedly denied the allegations, refused to stand down from the election and described the probe against him as "political assassination" .
Last week, Penelope Fillon broke her silence over the scandal and asserted she had carried out a "lot of different tasks" while she worked as a parliamentary assistant for her husband between 1998 and 2013.
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Over that time she earned €830,000 (£726,000), but investigative magazine Le Canard Enchaine said it could not find any evidence of work that had been carried out.
Mr Fillon was once considered to be the odds-on favourite to become the next French president, but the "Penelopegate" claims have badly dented his election hopes.
Polls show the 62-year-old languishing behind far-right candidate Marine Le Pen and centrist Emmanuel Macron on 20%.
The first round of the French election is on 23 April, with the top two candidates going head to head in a second round on 7 May.
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Mr Fillon's campaign was dealt a fresh blow over the weekend after his party tweeted a caricature with anti-Semitic overtones .
Les Republicains said it would launch an investigation into the post, which showed Mr Macron with a suit, top hat and hooked nose.
Meanwhile, Mr Fillon was also forced to respond to claims he was bought tens of thousands of euros of luxury suits by a mystery benefactor.